Bill Freeman wrote:

Guys,

The Internet is wonderful.  I used to spend my Saturdays at the local (KC)
Linda Hall Library (the finest private tech library in the world, no joke)
reading
old NACA reports and hand xeroxing the ones of interest at 10 cents per
page.  This was one of the ones I paid for - ---   now available on the
Langley NACA Tech Report server for free.

Check out:

http://naca.larc.nasa.gov/reports/1948/naca-rm-a7i30/

 then SHIFT-CLICK on the blue text line at the bottom which ends in "pdf"

it will take a while to download and you will need a free copy of Adobe
Acrobat to read it,but this is the REAL story, hard to get forever, now
readily available.  Enjoy - and cruise the "stacks" the 20s, 30s,40s and 50s
were when a lot of really smart folks were discovering a lot of neat
aero stuff and they wrote most of it down in these reports.

Bill Freeman

That is an incredible paper. 16 MB. Well worth the download time.
I notice the maximum pressure recovery is .86 for these ducts.
Formerly classified confidential.
This will answer Jerry's question about the parallel sides.

Paul Lamar
 
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